PROJECT SUMMARY An antibiotic susceptibility test determines whether or not bacterial isolates from a patient?s blood, wound specimens, or urine are susceptible to administered antibiotics. A standard antibiotic susceptibility test measures the growth of sampled bacteria in antibiotics and suffers from a long cell culture step. The lack of rapid antibiotic susceptibility tests adversely affects the treatment of bacterial infections and contributes to the increased prevalence of multidrug resistant bacteria. The focus of this R21 application is on urinary tract infections. In particular, a novel approach and device are proposed for rapidly determining the antibiotic susceptibility of bacteria in urine. Bacteria exhibit various types of movements, which appear to subside promptly upon exposure to an effective antibiotic. In the proposed study, the movements of bacteria that are causative pathogens for urinary tract infections will be measured before and after exposure to antibiotics. The magnitude of the measured bacterial movements will be correlated with antibiotic susceptibility. These measurements will be enabled by a novel tailor-made microfluidic transducer that converts bacterial movements into electrical signals with high fidelity. This device will interface with microfluidics and work with unprocessed urine samples. The proposed approach to antibiotic susceptibility testing is phenotypic, will eliminate the need for extensive culturing, and will allow for rapid testing. It is robust enough that it has the potential to be used at the point of care, when successfully developed. The aim and scope of the proposed study are clearly defined. This collaborative team consisting of experts in physical science (Ekinci), biological science (Stearns-Kurosawa), and clinical infectious diseases (Gupta) will be able to address any unforeseen challenges. Thus, the study has an excellent chance of success.